Technical Flat Tappet Cams Really Bad?

I'm wanting to install a Howard's Cams hydraulic flat tappet cam and lifters in a engine. I've read nothing good about flat tappet cams and lifters anywhere! I've read its all about the break in, oil, and valve springs. Can someone out there tell if going with a hydraulic flat tappet is good or bad? Of course I'm not building a SBC so the hydraulic roller lifters are stupid expensive! I can't justify nearly $1500-1800 in a stock engine!

 

The problem might not be with the cam or the lube, but it might be about how the lifters are made these days. I recently installed a new flat tappet cam with some decades old new stock lifters, no issues.

I also used my old lube method, of moly grease on the lobes and lifter faces.

If you have the old lifters, you could get the reground by a place like Delta Cams, and see how they do.

 

Flat tappet cams were used in millions of engines for years. In my mind, it is more about the application and break in. Granted lifter quality is not what it used to be. I used a flat tappet cam in my Buick Nail Head motor, but that has lighter valve spring pressures, and I used quality break in oil and proper break in procedures. I also used a flat tappet in an early SBF engine in my 53, but there again with reasonable valve spring pressures, good lifters and proper break in. Building an engine with high lift cams, heavy springs and high RPM would probably not be as successful.

 

There's millions still out there, running along, trouble free. It seems the majority of trouble comes from high lift, fairly aggressive cams with higher than normal spring pressure.
Be honest with yourself about intended usage. Do you REALLY need an aftermarket cam? Use high quality components to start with.
Also I've seen a lot of people using this transparent red assembly lube on the cam lobes. Personally, I wouldn't use that. I like the thick black molybdenum disulphide grease on the lobes and the lifter face. Then I use a good quality break-in oil, such as PennGrade straight 30wt break-in oil.
Others have their routines too. I have not had a cam go flat on the break-in in the over 50 years that I've been building my own engines. I've had one lobe failure in one of my drag race air-cooled VW motors. Those motors have 200lbs of seat pressure with 450lbs over the nose of the cam lobe. I chalk up this particular incident to a lack of maintenance on my part. I run methanol as fuel, and in that particular instance there was a lot of fuel contamination in the oil. I thought I could get away with "one more time" before changing oil. That motor had quite a few runs on it at the time.
I have also done some preventative inspection. There was a period of time when whoever was making the lifters were allowing some face run-out on lifters that should not have been sold. I had some brand new lifter re-ground to correct it. Lifter face run-out could cause the lifter to not rotate as the lobe lifted it, causing some failures out in the wild for those who did not check their parts.
Follow proper procedures, use good quality stuff, and a little prayer to the gods of speed, and you'll be in good shape!

 

As we all know, there have been tons of flat tappet lifter failures. Some people think that it's hard to get a good quality lifter anymore. I don't know on that, maybe it's true.
But one very important factor that is often overlooked on these old blocks: the lifter bores get worn out. If the lifter bore is oversized or out of round, the lifters don't rotate properly. It needs to be checked. Clearance should be .0012"--0018". The further out of spec it is, the more likely it is to fail. The solution is to bore them out for a larger lifter, or install bushings. If you have an uncommon engine, this can take some sleuthing to figure out what will work.
When the engine is being assembled, always verify lifter rotation on each and every lifter by barring over the engine and visually check in each one.
If it is a high performance cam with dual valve springs, do the break-in on single springs and then install the second springs after it is broken in.
When you first start the engine, run it at 2000 RPM for 20 minutes to break in the cam. It needs the RPM to splash enough oil onto the cam.

 

You have read that there are issues. You want to know if you can safely run them, even after reading about issues and not finding a clear answer. Yes, I will personally guarantee your engine and parts selection! Just send me a mere 15 thousand dollars insurance fee!

No really, there are problems and it's been discussed for at least a decade. Fingers have been pointed, but the bad things still happen. No one has been run out of business, no one has been compensated for time and money, the root cause has not been resolved. @squirrel has provided the most commonly agreed upon answer, but locating old NOS stuff is going to be more difficult and come with no warranty.
So you are still taking your chances.
You can discuss this with each company who sells what you are considering. Ask about it, get in writing what they will do in case there is a problem. The same caveat emptor (buyer beware) applies.

 

The only one I ever lost was a 454 with 85,000 on the engine in a crew cab . I like Iskys assembly cam lube. I agree with builders about spring pressure. In my opinion if your using stock or near pressure there is no need for lighter springs on break in. I’m talking 70-80 psi on the seat or less.
My sons dirt track engines using 130-140 on new flat tappet cams have never lost a cam either using Comp or Isky’s with the lube hole.

 

Did we go from horse/buggy to roller cams? Flats seemed cover the dead space quite nicely, for like 7 or so decades.

 

I use high zinc racing oil in my flat tappet cam engines and haven't had any problems, always heard the lack of zinc in the new oils was the problem. As stated above in several of the comments about using flat tappets for decades with out problems is true.

 

Get the hardness of the lifters checked. If they are too soft, they will fail.

 

Howards has a " No Fail" cam & kit , no matter what fails , it's covered , down side is a the iron filings that end up in your engine .

 

Don’t buy cheap lifters, don’t buy cheap cams, it costs to produce these things correctly out of the right materials. If lifters don’t have the correct radius they will die. If the cam is ground wrong same outcome. You can eyeball the radius on the lifter.

 

Watch the Videos on YouTube on cam and lifter design and how to recognise a dud.

 

Re: Howard Cams. When I built the Stude (SBC) I opted for a flat tappet version that had the warranty, had no problems with it, happy and less expensive than the Howard Roller that I put in the 38 Chevy. When I built the Track Roadster I thought I'd had good luck on the cam in the Stude so I bought the same cam. I thought I did the break in just like I did with the Stude but I didn't have much run time and had a flat cam. I got warranty on it and bought a Roller (which I now wish I had done the first time)

 

I've built 4 engines over the last 5 or 6 years. All were hydraulic flat tappet. Most were Elgin RV cams and lifters. One was a reground cam and refaced lifters done by Oregon Cam Grinding. My break-in was done with Rotella 15W-40 conventional oil, a bottle of Red Line Break-In additive and I coated the cam lobes and lifter faces with Red Line Assembly lube. I always primed the oil system, with the spark plugs out and slowly turned the engine through 2 crank rotations going 1/4 turn at a time and checking for oiling to the rocker arms (SBC). Always tried for a immediate start up and then 30-ish minutes at +/-2500 RPM, varying the RPM rather than just constant RPM. Perhaps it was just dumb luck but never had a cam problem.

After break in changed the oil and filter and went back with the Rotella and Red Line Break-In additive for at least the 1st oil and filter change.

YMMV

Lynn

 

Are the lifters with the small EDM'd (electrical discharge machined) holes in them still available ?

They squirt oil right onto the rubbing surface between the cam lobe and lifter. That should be good for saving the lifter and cam surface.

Mike

 

Some interesting remarks. I've read about getting old lifters resurfaced. I definitely agree with getting what you pay for. I've been reading more and more builders don't warranty or run a flat tappet. Not everyone can afford the roller stuff.

 

I always thought the EDM’d oil discharge lifters came about from NASCAR’s mandate that roller cams weren’t allowed. With increasingly higher spring rates cam failures became more common and the extra oiling helped. A good lifter and proper break in lube will suffice with the average street cam.

 

This is close to what I do. I've done 40 to 50 FT cam installs. Never had one go bad, so my ancient ritual must be working.

I use a high zinc oil like Lucas or Brad Penn. Change the oil and filter after the break in. Also I make sure the engine will run the entire break in and not overheat.

 

Which engine? Some parts are easier to source than others.

 

The local shop that does my engines will no longer build motors with flat tappet cams, only rollers. They claim their failure rate was to high? I've never had a problem as long as I followed the cam makers instructions. I have been doing some crate engine shopping both GM & Blue Print and everything I looked at had a roller, even some of the GM crates that had been flat tappet were now rollers.

 

comp cams 5003 lifter bore grooving tool a bit pricey but you and all your small block chevy friends will all use it the downside it has to be done before assembly

 

https://www.chevyhardcore.com/tech-...he-quality-of-life-for-flat-tappet-camshafts/

 

Some vintage engines don’t have the luxury of having roller cams as an option… And in many of those cases it’s not exactly like premium parts options are on the table either. You buy a set of new lifters and they come in a blank white box, probably from China.

On something like an SBC where none of that is true, if you follow the advice here and don’t overthink it, you shouldn’t have any problems.

 

If you get a bad cam or bad lifters, which happens more these days due to different sources making them nowadays.....nothing you do will prevent wiping the cam and lifters.



The above info is from Billy Godbolt, the former camshaft guru at Comp cams.




Click on picture so you can read the info...

Yes, its not cheap. I bit the bullet for my Cad build because I can't afford " Not To". There is a lot of expense in building an engine, and I'd rather force myself to pay more for the upgraded roller parts than chance ruining all those other expensive parts. With todays 3 month lead times, you can save up enough money for the more better stuff.

 

Iskys and Comps are different designs. Comps hole is in the center and Iskys near the edge.

Most folks don’t remember the earlier SBC’s had a notch in their rod cap and a hole splitting the rod and cap bearing to squirt oil on the cylinder walls and CAMSHAFT and LIFTERS and we never heard of a camshaft failure. In the 70’s all that was removed and we started seeing camshaft failures. Now it’s lifters and to me could be an oiling problem also. Also if your builder keeps the rod side play clearance on the tight side that also slows the oil from reaching the cam and lifters. The racing engine I assembled for me and my son all would have what some would say is excessive rod side clearance…but we have never lost a cam or lifters…

 

I believe it's the most over thunk subject. Cleanliness on assembly, good parts, proper lubrication, ensure that the lifters spin freely in the bore without slop, proper cam timing on assembly. When I was younger, break in was described as bringing the engine up in rpm to increase oil sling and flow, I was told 40 years ago to add an extra quart of oil on initial fire up for this reason. I've had one lifter/cam failure in many many sbc builds, it was a comp thumper cam, with cheap pbm lifters, and my fuck up on timing chain install, because the gear had a double stamp that even my machinist was baffled by. That's when I learned about Johnson hy-lift lifters. Don't be afraid. I've seen more roller lifters fail than flat tappet around my town.

 

Before you put the intake on, crank the engine by hand to assure the lifters spin. It's good, cheap insurance.

 

It's been a decade since I built the SBC in my '37 Austin gasser and back then I refused to go to the expense of a roller cam and retrofit lifters. I went with an Isky cam and flat tappets and it's been great. I did have one issue with the wire clips popping off the lifters one year at the drags. Lost 3 lifters and shut down my racing that day. I got new lifters warranted from Isky and changed all the wire clips out to internal snap rings, and reassembled the engine. Been perfect ever since.
My last SBC build in 2020 is a 1990 SBC roller motor, and it had a new cam and lifters in it when I bought the block. Seller said it was an "RV cam" and didn't know specs, so I tossed it and bought a roller camshaft from Howards. Love it, and if I ever build another it will also be a roller cam.
I know friends who are anal about building engines, and use all the correct assembly lube, breakin time, breakin oil, etc. and still had their flat tappet cams go flat. I doubt most cams that go flat were caused by poor setup, lube or breakin time. I just don't trust the current flat tappet lifters, and I'm not hearing anything from any cam maker that tells me one is any better than the others.

 

Just broke in this BBC comp cam. Pulled intake to fix vacuum leaks, cam lobes look good, watched pushrods from start.....all spinning fast.

Replaced his Holley Strip Dominator intake with a lower volume Edelbrock Torquer 2-0. Runs great, starts like a champ.

We good to go.